The present invention is directed to a method for monitoring the fees arising for calls in a mobile radiotelephone system.
It is known to levy the fees arising for calls in a telephone system as a function of the service respectively used by the subscribers, these fees being composed of fixed monthly charges and/or variable call charges. The payment ensues by cash payment, by employing telephone cards or by debiting from an account. In a mobile radiotelephone system, the charges arising during a call are evaluated, for example, in real time and are collected in a debit center for billing. This causes a considerable signalling load in the mobile radiotelephone system.
It is desirable to limit the fees that arise due to redirected and/or forwarded calls since mobile radiotelephone subscribers have themselves called by appointment in order to activate the destination number requested by a caller (for example, from a foreign country) to the which the call is to be redirected or forwarded. In this way, the mobile radiotelephone subscriber repeatedly appears as a switching center, so that potentially expensive call (for example, longer-duration international calls) are conducted via the subscriber without the operator of the mobile radiotelephone system being able to monitor the charges. When the caller making use of the call forwarding or the call transfer does not pay the charges, then the mobile radiotelephone system is being fraudulently used. A high signalling load arises when a call forwarding or a call transfer is active for mobile radiotelephone subscribers and every forwarded or transferred call must be reported to a central location in the mobile radiotelephone system for monitoring reasons.